The present invention relates generally to a variable capacity swash plate type compressor adapted for use in an air conditioning system for a vehicle. In particular, this invention relates to a swash plate type compressor having an inlet port disposed in the crankcase for fluid communication with the crank chamber and an outlet port disposed in a cylinder head for fluid communication with the discharge chamber to increase the capacity of the compressor, and eliminate the requirement for an orifice tube in fluid communication between the crank chamber and the discharge chamber.
Variable capacity swash plate type compressors typically include a cylinder block provided with a number of cylinders, a piston disposed in each of the cylinders of the cylinder block, a rotatably supported drive shaft, and a swash plate. The swash plate is adapted to be rotated by the drive shaft. The rotation of the swash plate is effective to reciprocatively drive the pistons. The length of the stroke of the piston is varied by an inclination angle of the swash plate. The inclination angle of the swash plate is varied by controlling the pressure differential between a suction chamber and a crank chamber using a control valve. An orifice tube is also typically disposed to provide fluid communication between a discharge chamber and the crank chamber to recirculate compressed gases from the discharge chamber to the crank chamber.
In the prior art, the crank chamber has been an inactive part of the compressor flow strategy. The crank chamber pressure is typically regulated by monitoring the suction pressure of the suction chamber and the discharge pressure of the discharge chamber. The refrigerant gases travel through the compressor after initially being introduced through an inlet port disposed in the cylinder head of the compressor and thence to the suction chamber. The refrigerant gases are then introduced into the cylinders and expelled from the cylinders into the discharge plenum. A control valve is provided to control the flow of refrigerant gas between the suction chamber and the crank chamber depending on the pressure differential between the two chambers. Once in the discharge plenum, the refrigerant gases are expelled through an outlet port disposed in the cylinder head of the compressor or through the orifice tube to the crank chamber.
The compressor arrangement in the prior art described above has several disadvantages. First, the capacity of the compressor is reduced due to the presence of the orifice tube where high-pressure refrigerant gases are passed to the crank chamber and are not used in the cooling portion of the air-conditioning system. Second, due to the introduction of refrigerant gases through the inlet port into the relatively small suction chamber, vibration occurs requiring the use of a muffler in the inlet port or outlet port to dampen the vibration. Finally, effective lubrication of the close tolerance moving parts within the crank chamber due to the lack of a consistent flow through the crank chamber is also a concern.
An object of the invention is to produce a swash plate type compressor wherein the capacity of the compressor is maximized.
Another object of the invention is to produce a swash plate type compressor wherein the vibration of the compressor components is minimized to result in smoother operation of the compressor.
Another object of the invention is to produce a swash plate type compressor wherein the durability and duty cycle of the compressor are maximized.
Still another object of the invention is to produce a swash plate type compressor wherein lubrication is provided to the compressor components.
The present invention includes a variable capacity swash plate type compressor including a cylinder block; a cylinder head attached to the cylinder block and cooperating with the cylinder block to form an airtight seal, the cylinder head having a suction chamber and a discharge chamber formed therein; a crankcase attached to the cylinder block and cooperating with the cylinder block to define an airtight sealed crank chamber; a first conduit means providing fluid communication between the crank chamber and a source of refrigerant gas; and a second conduit means for exhausting refrigerant gas from the discharge chamber.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings.